1. Field of Invention
The invention relates to a digital image processing method and, in particular, to an exposure correction method for digital images.
2. Related Art
Due to the popularity of digital cameras and scanners, there are more chances for people to obtain digital images. However, such pictures sometimes do not have appropriate exposure. They are either over exposed (the images being too bright) or insufficiently exposed (the images being too dark). All these situations directly affect the visual effects of the images. Therefore, they have to be corrected in order to have better effects.
The exposure correction can increase or decrease the exposure amount of an image. More exposure gives a brighter image to reveal more details. Less exposure makes the image darker, rendering fewer details.
The conventional exposure correction method is performed in the RGB format. Since all channels are implemented using the method of Gamma Normalization, it thus takes a longer processing time. The conventional method uses the maximum and minimum of the brightness to determine the gamma curve and a luminance lookup table. The effect of such a processing method is not ideal.
Therefore, how to provide a digital image processing method to enhance the image processing effect while increasing the exposure correction speed is a problem to be solved in the field.